FIG. 1 illustrates a prior art switching power supply with output current sensing as disclosed in U.S. Pat. No. 6,683,441. The system of FIG. 1 includes a controller 20 that generates switching control signals SC1 and SC2 to drive switch circuits 10 and 12, thereby controlling the amount of power delivered to the load 22 through inductors 14 and 16. Additional circuitry would typically be included to sense the output voltage VOUT so the controller can modulate the switch signals to maintain a constant output voltage regardless of the amount of current consumed by the load. The sensed output voltage is usually combined with an input signal to generate an error signal that is applied to the controller for closed-loop control of the output. Additional components such as capacitors would typically also be added for filtering the output voltage.
The system of FIG. 1 also includes a current sensing circuit 18 to generate a signal VCS that provides a measure of the total combined output current delivered to the load. The current sense signal may be used in numerous ways. For example, it may be used to provide over-current shutdown, it may be used to implement current-mode regulation, or it may be combined with voltage feedback to establish a droop impedance for adaptive voltage positioning (AVP) control schemes.
The system of FIG. 1 is known as a multi-phase switching power supply because the power components including the switches and inductors are repeated to produce multiple output currents that are summed together to provide the total output current. This increases the amount of current available from the power supply, but also increases the complexity of the controller and sensing circuits.